Ohale L O, Ghoshal N G
Res Vet Sci. 1982 Sep;33(2):243-7.
A reversible tracheal cannula was implanted in 14 Rambouillet sheep so that the sheep could breathe normally through the nostrils when the 'flow-through' insert was in place or through the tracheal opening when the 'bypass' insert of the cannula was in place. The outer diameter of the superotemporal retinal vein increased significantly in size during nasal bypass breathing compared to normal nasal breathing. Anteroposterior histological sections of the retina and optic disc revealed disc elevation and marked venous engorgement during nasal bypass breathing. These results suggest that a possible increase in the cerebrospinal fluid pressure during nasal bypass breathing must have caused a corresponding increase in optic nerve tissue pressure resulting in axoplasmic flow stasis and swelling of the optic nerve axons in the prelaminar area of the optic disc. The swollen axons apparently caused the compression of the thin-walled retinal veins resulting in venous engorgement.
在14只朗布依埃羊身上植入了可逆气管插管，这样当“流通”插入物就位时，羊可以通过鼻孔正常呼吸；当插管的“旁路”插入物就位时，羊可以通过气管开口呼吸。与正常鼻腔呼吸相比，在鼻腔旁路呼吸期间，颞上视网膜静脉的外径显著增大。视网膜和视盘的前后组织学切片显示，在鼻腔旁路呼吸期间视盘抬高且静脉明显充血。这些结果表明，鼻腔旁路呼吸期间脑脊液压力可能升高，这必然导致视神经组织压力相应升高，从而导致轴浆流停滞和视盘层前区视神经轴突肿胀。肿胀的轴突显然导致了薄壁视网膜静脉受压，进而导致静脉充血。
